The present invention relates to a fuel cell system, and particularly to a fuel cell system capable of efficiently discharging liquid remaining in a fuel cell stack at the time of actuation of the fuel cell and liquid discharging method for the same.
A Fuel cell has attracted attention as an environmentally friendly, clean power source. The fuel cell uses fuel gas such as hydrogen and oxidation gas such as air to generate power by an electrochemical reaction. Water (water vapor) is also generated by the electrochemical reaction of fuel gas with oxidation gas. Thus, the generated water is discharged appropriately during the operation of the fuel cell.
When the operation of the fuel cell is restarted after it is once stopped, however, the generated water and the dew condensation water remaining in the fuel cell stack would hinder smooth restart thereof if they are not removed. Although it may be conceivable to remove the generated water and the dew condensation water by causing a circulating pump in a fuel gas circulating system to operate at a high speed, it will increase the noise.
Japanese Patent Laid-Open No. 2003-317766 discloses a configuration where a purge valve is disposed in a fuel gas circulating system, and the purge valve is made open upon occurrence of clogging of drain to temporarily increase the flow rate of fuel gas to thereby solve the clogging of drain.
However, It is difficult to fully discharge the liquid in the system (the generated water, dew condensation water) by simply increasing the flow rate of fuel gas.